"Did someone say poof?" This is the side-splitting first line shrieked by Al Murray's gay Nazi character Horst Schwull as he bursts into Hitler's office on the comedian's new sketch show tonight. What follows is the most outrageously homophobic few minutes of television "comedy" this country has seen.

We know the character is gay because of a series of subtle clues. These include Schwull's pink rubber Gestapo uniform, his dyed blond bouffant hair, his makeup, limp wrists and propensity to mime fellatio and anal sex.

The visuals, however, are but an amuse bouche to the main course of "gags" comprised solely of the kind of gross stereotypes and crass double entendres that would have seemed lazy and offensive even in a 1970s working man's club. Here's an exchange between Schwull (played by Murray) and the Hitler character:

Hitler: We have a dangerous mission for you if you are interested in the challenge.Schwull: Oooh, the bit I am chomping on, my fabulous leader – fill me in! [Turning round and offering Hitler his bottom]H: You have a background in musical theatre, do you not?S: Oh ja, I am very at home in Cole Porter.H: The plans is as follows: in order to maintain morale allied forces are regularly entertained by so-called concert parties. You will assume the identity of one of the performers.S: I love to go under covers with the boys!

And so it goes on, relentlessly. This is not post-modern irony; this is not a knowing in-joke, this is not exposing the prejudice of others as Sacha Baron Cohen's Bruno does. It merely exposes the prejudice of Murray and seeks to inflame that of others.

But while the mincing, screaming sexual predator antics are distasteful enough in pandering to every nasty lie propagated about gay people, it's the backdrop that renders them truly galling. Namely, Nazi Germany. As a history graduate from Oxford, Murray should know this period, but perhaps he needs a reminder.

From 1933 onwards, gay people were the lowest of the low in the Third Reich. As Martin Sherman so brilliantly evokes in his play Bent, you were better off in a concentration camp with a Star of David stuck to your chest than a pink triangle. Castration, torture and enforced medical experiments were commonplace for homosexuals. Tens of thousands died.

So while Murray's Hitler commands Schwull to infiltrate enemy camp, in reality, the only orders Hitler gave gay people were for their deaths. And we are supposed to laugh at this sketch? Imagine if the character of Schwull was Jewish. And he was shown guzzling chicken soup, while re-enacting Yentl, taking money out of Hitler's pocket and attempting to slash off every foreskin in sight. It is unthinkable. Yet unlike antisemitism, homophobia is apparently acceptable on British television. As such, ITV1 should take Murray's programme off the air before issuing a joint apology with Murray for the offence caused. Not least to the few remaining gay victims of Nazi Germany. For them, at least, respect should be shown. That we are currently in Lesbian Gay Bisexual and Transgender History Month, which seeks to raise awareness of this community's past struggles, makes the timing particularly ill-judged.

But there is one final insult. The gay Nazi character's surname is Schwull. Schwul is the German word for gay. Thus, the dehumanisation is complete. Gay people are nothing more than gay. Again, imagine, say, there was a jihadi character whose last name was Muslim. It would never make it on to our screens. Yet when I contacted Murray's publicist to put these allegations of homophobia to him, no response came back.

Whatever ITV1 decides to do with Al Murray's Multiple Personality Disorder one can only hope there won't be a second series, as on his descent into offensive comedy hell, who knows what audiences might be subjected to. A hilarious sketch set in Guantánamo Bay with an Osama bin Laden lookalike? Or maybe just a laughter track set over footage of a Rwandan rape camp?

Given the comments under this sketch's posting on YouTube, the most certain damage done to Murray's career will come not from ITV's bosses but from the simple, joyous fact that people just aren't remotely amused.

So, Mr Murray – or should I call you Mr Straight? – I, along with every other LGBT person, will start laughing when you and the rest of the world stop hating. Or perhaps when you finally say something funny.